1. Field of the Invention
This invention relates to an optical device and a method for aiming and visually indicating a reading area. In particular, the invention relates to an optical device and a method for aiming a reading area, so as to provide an operator with a visual indication of the framed area allowing him to more conveniently read the enclosed information therein, e.g. object-identifying information contained in optical codes applied to the objects.
The invention also relates to a device and a method for determining the distance from and the orientation of the reading area with respect to the device.
2. Discussion of Prior Art
Optical aiming devices are known which can provide an operator with a visual indication of a framed area. In particular, it is known to use such devices in optical readers to allow the reader to be properly positioned over an area containing the information to be read, thereby to optimize subsequent reading operations.
Such aiming devices typically comprise a plurality or emission sources adapted to project respective light beams onto end portions of the framed area to obtain each time a visual indication of the framed area border edges, and hence of the field or view subtended by the reader.
In general, the emission sources used in such devices are LED or laser sources.
LED-based aiming devices are relatively inexpensive and of simple construction, but they have a drawback in that the light beams emitted by them are poorly collimated and, consequently, produce not bright and clear images on the illuminated surfaces. LED devices are therefore suitable for illuminating reading areas which are placed very close.
On the other hand, many applications of optical readers demand that a clear sharp indication of the border edges of the area subtended by the reader be provided. For the purpose, laser aiming devices have been developed which emit well collimated and defined light beams through a great depth of field.
However, laser devices have a major drawback in their high cost.